#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>

int main()
{
	int count = 0;
	int bot_drk = 20;

	do
	{
		count = count+bot_drk;
		bot_drk = bot_drk / 2;
	} while (bot_drk >= 2);

	printf("%d", count);

	return 0;
}